用简便方法计算:(1)83*77 (2)1.2²*9-1.3²*4 (3) 16.8*15/32+7.6*15/16 (因式分解)
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![用简便方法计算:(1)83*77 (2)1.2²*9-1.3²*4 (3) 16.8*15/32+7.6*15/16 (因式分解)](/uploads/image/z/65713-49-3.jpg?t=%E7%94%A8%E7%AE%80%E4%BE%BF%E6%96%B9%E6%B3%95%E8%AE%A1%E7%AE%97%EF%BC%9A%281%2983%2A77+%282%291.2%26%23178%3B%2A9-1.3%26%23178%3B%2A4+%283%29+16.8%2A15%2F32%2B7.6%2A15%2F16+%28%E5%9B%A0%E5%BC%8F%E5%88%86%E8%A7%A3%29)
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用简便方法计算:(1)83*77 (2)1.2²*9-1.3²*4 (3) 16.8*15/32+7.6*15/16 (因式分解)
用简便方法计算:(1)83*77 (2)1.2²*9-1.3²*4 (3) 16.8*15/32+7.6*15/16 (因式分解)
用简便方法计算:(1)83*77 (2)1.2²*9-1.3²*4 (3) 16.8*15/32+7.6*15/16 (因式分解)
(1)83*77
解原式=(80+2)(80-3)
=6400-9
=6391
(2)1.2²*9-1.3²*4
解原式=(1.2×3-1.3×2)(1.2×3+1.3×2)
=(3.6-2.6)(3.6+2.6)
=1×6.2
=6.2
(3) 16.8*15/32+7.6*15/16
解原式=15/16(16.8×1/2+7.6)
=15/16(8.4+7.6)
=(15/16)×16
=15